[Clang][ARM] Define __VFP_FP__ macro unconditionally

Clang only defines __VFP_FP__ when the FPU is enabled. However, gcc
defines it unconditionally.

This patch aligns Clang with gcc.

Reviewed By: peter.smith, rengolin

Differential Revision: https://reviews.llvm.org/D100372

Author: vhscampos

clang/lib/Basic/Targets/ARM.cpp

@@ -755,8 +755,12 @@ void ARMTargetInfo::getTargetDefines(const LangOptions &Opts,
   // Note, this is always on in gcc, even though it doesn't make sense.
   Builder.defineMacro("__APCS_32__");
 
+  // __VFP_FP__ means that the floating-point format is VFP, not that a hardware
+  // FPU is present. Moreover, the VFP format is the only one supported by
+  // clang. For these reasons, this macro is always defined.
+  Builder.defineMacro("__VFP_FP__");
+
   if (FPUModeIsVFP((FPUMode)FPU)) {
-    Builder.defineMacro("__VFP_FP__");
     if (FPU & VFP2FPU)
       Builder.defineMacro("__ARM_VFPV2__");
     if (FPU & VFP3FPU)

clang/test/Preprocessor/arm-target-features.c

@@ -141,6 +141,11 @@
 // CHECK-V7S-NOT: __ARM_FEATURE_DIRECTED_ROUNDING
 // CHECK-V7S: #define __ARM_FP 0xe
 
+// RUN: %clang -target arm-arm-none-eabi -march=armv7-m -mfloat-abi=soft -x c -E -dM %s | FileCheck -match-full-lines --check-prefix=CHECK-VFP-FP %s
+// RUN: %clang -target arm-arm-none-eabi -march=armv7-m -mfloat-abi=softfp -x c -E -dM %s | FileCheck -match-full-lines --check-prefix=CHECK-VFP-FP %s
+// RUN: %clang -target arm-arm-none-eabi -march=armv7-m -mfloat-abi=hard -x c -E -dM %s | FileCheck -match-full-lines --check-prefix=CHECK-VFP-FP %s
+// CHECK-VFP-FP: #define __VFP_FP__ 1
+
 // RUN: %clang -target armv8a -mfloat-abi=hard -x c -E -dM %s | FileCheck -match-full-lines --check-prefix=CHECK-V8-BAREHF %s
 // CHECK-V8-BAREHF: #define __ARMEL__ 1
 // CHECK-V8-BAREHF: #define __ARM_ARCH 8